Curses From Different Necros

Necromancer
1

I seem to recall that in D2 LOD curses from different necromancers stacked. For example, if Necro A cast Amplify Damage and Necromancer B cast Weaken, the mob would be affected by both.

Yesterday I did a Baal run with another necromancer, but our curses did not stack. Has anyone else noticed this issue?

2

You remember wrong, curses never stacked.
The only exception is Attract, which is not overridden by other curses.